Neuhuber Franz, Dunkelmann Bettina, Grießner Ines, Helm Katharina, Kayser Manfred, Ralf Arwin
Department of Forensic Medicine and Forensic Neuropsychiatry, University of Salzburg, Salzburg, Austria.
Department of Genetic Identification, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
Forensic Sci Int Genet. 2022 May;58:102682. doi: 10.1016/j.fsigen.2022.102682. Epub 2022 Feb 24.
The discovery of rapidly mutating (RM) Y-STRs started to move the field of forensic Y-STR analysis from male lineage identification towards male individual identification. Previously, the forensic value of RM Y-STRs for differentiating male relatives was limited due to the modest number of 13 identified RM Y-STRs. Recently, new RM Y-STRs were discovered, with strong expectations for significantly improving male relative differentiation; however, empirical evidence is missing yet. More recently, the genotyping method RMplex for efficiently analyzing 30 Y-STRs with high mutation rates, including all 26 currently known RM Y-STRs, was introduced. Here, we applied RMplex as well as the current state-of-the-art commercial Y-STR kit: Yfiler™ Plus PCR Amplification kit, to several hundreds of DNA-confirmed father-son pairs. Newly established estimates confirmed the high mutation rates of novel and previous RM Y-STRs. By combining current with previous data, we provide updated consensus estimates of mutation rates for all 49 Y-STRs targeted with both methods. Based on RMplex, 42% of 499 father-son pairs were differentiated, while 14% of 530 pairs based on Yfiler™ Plus, and 48% of 499 pairs based on both methods combined. Regarding brothers, RMplex also clearly outperformed Yfiler™ Plus, with differentiation rates of 62% and 33%, respectively. By combining both methods 72.9% of the brothers showed at least one mutation. For unrelated males, both methods achieved a discrimination capacity of 99.8% and a haplotype diversity of 0.999991, since all males had different haplotypes, except for two, perhaps indicating a hidden paternal relationship. Overall, this study underlines the value of RM Y-STRs in general and RMplex in particular for differentiating male relatives highly relevant in forensic genetics. It provides the first empirical evidence on the high value of RMplex for differentiating close male relatives, which for father-son pairs was almost 60% higher than with the initial set of 13 RM Y-STRs and three times higher than with Yfiler™ Plus. Based on our results from closely related males, we expect RMplex to also improve the differentiation of more distantly related males significantly, which needs empirical demonstration in future studies. We encourage the forensic community to apply RMplex in all forensic cases where a match with a commercial Y-STR kit was obtained between the male suspect and the evidence material, or to solely use RMplex in such cases, aiming to find out if the male suspect or any of his male paternal relatives left the evidence material at the crime scene.
快速突变（RM）Y-STR的发现开始推动法医Y-STR分析领域从男性谱系鉴定向男性个体鉴定发展。此前，由于已鉴定出的13个RM Y-STR数量有限，RM Y-STR在区分男性亲属方面的法医价值受到限制。最近，发现了新的RM Y-STR，人们对其显著改善男性亲属区分能力寄予厚望；然而，尚无实证证据。最近，引入了RMplex基因分型方法，可有效分析30个具有高突变率的Y-STR，包括目前已知的所有26个RM Y-STR。在此，我们将RMplex以及当前最先进的商业Y-STR试剂盒：Yfiler™ Plus PCR扩增试剂盒，应用于数百对经DNA确认的父子对。新确定的估计值证实了新的和先前的RM Y-STR具有高突变率。通过结合当前和先前的数据，我们提供了两种方法所针对的所有49个Y-STR突变率的最新共识估计值。基于RMplex，499对父子对中有42%得以区分，基于Yfiler™ Plus的530对父子对中有14%得以区分，两种方法结合则499对父子对中有48%得以区分。对于兄弟而言，RMplex同样明显优于Yfiler™ Plus，区分率分别为62%和33%。通过结合两种方法，72.9%的兄弟至少出现了一处突变。对于无关男性，两种方法的鉴别能力均达到99.8%，单倍型多样性为0.999991，因为除了两人之外所有男性的单倍型均不同，这或许表明存在潜在的父系关系。总体而言，本研究强调了RM Y-STR尤其是RMplex在区分法医遗传学中高度相关的男性亲属方面的价值。它提供了首个关于RMplex在区分近亲男性亲属方面具有高价值的实证证据，对于父子对而言，其区分能力比最初的13个RM Y-STR高出近60%，比Yfiler™ Plus高出三倍。基于我们对近亲男性的研究结果，我们预计RMplex也能显著改善对更远亲男性的区分能力，这需要在未来研究中进行实证验证。我们鼓励法医界在男性嫌疑人与证据材料之间获得与商业Y-STR试剂盒匹配结果的所有法医案件中应用RMplex，或者在此类案件中仅使用RMplex，以查明男性嫌疑人或其任何男性父系亲属是否在犯罪现场留下了证据材料。
